rxkad.c 27.9 KB
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/* Kerberos-based RxRPC security
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <crypto/skcipher.h>
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#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/scatterlist.h>
#include <linux/ctype.h>
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#include <linux/slab.h>
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#include <net/sock.h>
#include <net/af_rxrpc.h>
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#include <keys/rxrpc-type.h>
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#include "ar-internal.h"

#define RXKAD_VERSION			2
#define MAXKRB5TICKETLEN		1024
#define RXKAD_TKT_TYPE_KERBEROS_V5	256
#define ANAME_SZ			40	/* size of authentication name */
#define INST_SZ				40	/* size of principal's instance */
#define REALM_SZ			40	/* size of principal's auth domain */
#define SNAME_SZ			40	/* size of service name */

struct rxkad_level1_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
};

struct rxkad_level2_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
	__be32	checksum;	/* decrypted data checksum */
};

/*
 * this holds a pinned cipher so that keventd doesn't get called by the cipher
 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
 * packets
 */
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static struct crypto_skcipher *rxkad_ci;
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static DEFINE_MUTEX(rxkad_ci_mutex);

/*
 * initialise connection security
 */
static int rxkad_init_connection_security(struct rxrpc_connection *conn)
{
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	struct crypto_skcipher *ci;
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	struct rxrpc_key_token *token;
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	int ret;

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	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->params.key));
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	token = conn->params.key->payload.data[0];
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	conn->security_ix = token->security_index;
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	ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
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	if (IS_ERR(ci)) {
		_debug("no cipher");
		ret = PTR_ERR(ci);
		goto error;
	}

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	if (crypto_skcipher_setkey(ci, token->kad->session_key,
				   sizeof(token->kad->session_key)) < 0)
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		BUG();

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	switch (conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
		break;
	case RXRPC_SECURITY_AUTH:
		conn->size_align = 8;
		conn->security_size = sizeof(struct rxkad_level1_hdr);
		conn->header_size += sizeof(struct rxkad_level1_hdr);
		break;
	case RXRPC_SECURITY_ENCRYPT:
		conn->size_align = 8;
		conn->security_size = sizeof(struct rxkad_level2_hdr);
		conn->header_size += sizeof(struct rxkad_level2_hdr);
		break;
	default:
		ret = -EKEYREJECTED;
		goto error;
	}

	conn->cipher = ci;
	ret = 0;
error:
	_leave(" = %d", ret);
	return ret;
}

/*
 * prime the encryption state with the invariant parts of a connection's
 * description
 */
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static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
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{
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	struct rxrpc_key_token *token;
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	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
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	struct scatterlist sg;
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	struct rxrpc_crypt iv;
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	__be32 *tmpbuf;
	size_t tmpsize = 4 * sizeof(__be32);
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	_enter("");

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	if (!conn->params.key)
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		return 0;

	tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
	if (!tmpbuf)
		return -ENOMEM;
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	token = conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	tmpbuf[0] = htonl(conn->proto.epoch);
	tmpbuf[1] = htonl(conn->proto.cid);
	tmpbuf[2] = 0;
	tmpbuf[3] = htonl(conn->security_ix);
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	sg_init_one(&sg, tmpbuf, tmpsize);
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	skcipher_request_set_tfm(req, conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv));
	kfree(tmpbuf);
	_leave(" = 0");
	return 0;
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}

/*
 * partially encrypt a packet (level 1 security)
 */
static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
				    struct sk_buff *skb,
				    u32 data_size,
				    void *sechdr)
{
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxkad_level1_hdr hdr;
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	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u16 check;

	sp = rxrpc_skb(skb);

	_enter("");

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	check = sp->hdr.seq ^ sp->hdr.callNumber;
	data_size |= (u32)check << 16;
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	hdr.data_size = htonl(data_size);
	memcpy(sechdr, &hdr, sizeof(hdr));
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	/* start the encryption afresh */
	memset(&iv, 0, sizeof(iv));

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	sg_init_one(&sg, sechdr, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	_leave(" = 0");
	return 0;
}

/*
 * wholly encrypt a packet (level 2 security)
 */
static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
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				       struct sk_buff *skb,
				       u32 data_size,
				       void *sechdr)
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{
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	const struct rxrpc_key_token *token;
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	struct rxkad_level2_hdr rxkhdr;
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	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
	struct scatterlist sg[16];
	struct sk_buff *trailer;
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	unsigned int len;
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	u16 check;
	int nsg;
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	int err;
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	sp = rxrpc_skb(skb);

	_enter("");

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	check = sp->hdr.seq ^ sp->hdr.callNumber;
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	rxkhdr.data_size = htonl(data_size | (u32)check << 16);
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	rxkhdr.checksum = 0;
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	memcpy(sechdr, &rxkhdr, sizeof(rxkhdr));
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	/* encrypt from the session key */
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	token = call->conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
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	crypto_skcipher_encrypt(req);
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	/* we want to encrypt the skbuff in-place */
	nsg = skb_cow_data(skb, 0, &trailer);
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	err = -ENOMEM;
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	if (nsg < 0 || nsg > 16)
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		goto out;
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	len = data_size + call->conn->size_align - 1;
	len &= ~(call->conn->size_align - 1);

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	sg_init_table(sg, nsg);
	skb_to_sgvec(skb, sg, 0, len);
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	skcipher_request_set_crypt(req, sg, sg, len, iv.x);
	crypto_skcipher_encrypt(req);
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	_leave(" = 0");
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	err = 0;

out:
	skcipher_request_zero(req);
	return err;
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}

/*
 * checksum an RxRPC packet header
 */
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static int rxkad_secure_packet(struct rxrpc_call *call,
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			       struct sk_buff *skb,
			       size_t data_size,
			       void *sechdr)
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{
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u32 x, y;
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	int ret;

	sp = rxrpc_skb(skb);

	_enter("{%d{%x}},{#%u},%zu,",
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	       call->debug_id, key_serial(call->conn->params.key),
	       sp->hdr.seq, data_size);
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	if (!call->conn->cipher)
		return 0;

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	ret = key_validate(call->conn->params.key);
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	if (ret < 0)
		return ret;

	/* continue encrypting from where we left off */
	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));

	/* calculate the security checksum */
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	x = call->channel << (32 - RXRPC_CIDSHIFT);
	x |= sp->hdr.seq & 0x3fffffff;
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	call->crypto_buf[0] = htonl(sp->hdr.callNumber);
	call->crypto_buf[1] = htonl(x);
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	sg_init_one(&sg, call->crypto_buf, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	y = ntohl(call->crypto_buf[1]);
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	y = (y >> 16) & 0xffff;
	if (y == 0)
		y = 1; /* zero checksums are not permitted */
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	sp->hdr.cksum = y;
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	switch (call->conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
		ret = 0;
		break;
	case RXRPC_SECURITY_AUTH:
		ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr);
		break;
	case RXRPC_SECURITY_ENCRYPT:
		ret = rxkad_secure_packet_encrypt(call, skb, data_size,
						  sechdr);
		break;
	default:
		ret = -EPERM;
		break;
	}

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	_leave(" = %d [set %hx]", ret, y);
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	return ret;
}

/*
 * decrypt partial encryption on a packet (level 1 security)
 */
static int rxkad_verify_packet_auth(const struct rxrpc_call *call,
				    struct sk_buff *skb,
				    u32 *_abort_code)
{
	struct rxkad_level1_hdr sechdr;
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
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	struct scatterlist sg[16];
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	struct sk_buff *trailer;
	u32 data_size, buf;
	u16 check;
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	int nsg;
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	_enter("");

	sp = rxrpc_skb(skb);

	/* we want to decrypt the skbuff in-place */
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	nsg = skb_cow_data(skb, 0, &trailer);
	if (nsg < 0 || nsg > 16)
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		goto nomem;

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	sg_init_table(sg, nsg);
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	skb_to_sgvec(skb, sg, 0, 8);
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	/* start the decryption afresh */
	memset(&iv, 0, sizeof(iv));

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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
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	/* remove the decrypted packet length */
	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
		goto datalen_error;
	if (!skb_pull(skb, sizeof(sechdr)))
		BUG();

	buf = ntohl(sechdr.data_size);
	data_size = buf & 0xffff;

	check = buf >> 16;
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	check ^= sp->hdr.seq ^ sp->hdr.callNumber;
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	check &= 0xffff;
	if (check != 0) {
		*_abort_code = RXKADSEALEDINCON;
		goto protocol_error;
	}

	/* shorten the packet to remove the padding */
	if (data_size > skb->len)
		goto datalen_error;
	else if (data_size < skb->len)
		skb->len = data_size;

	_leave(" = 0 [dlen=%x]", data_size);
	return 0;

datalen_error:
	*_abort_code = RXKADDATALEN;
protocol_error:
	_leave(" = -EPROTO");
	return -EPROTO;

nomem:
	_leave(" = -ENOMEM");
	return -ENOMEM;
}

/*
 * wholly decrypt a packet (level 2 security)
 */
static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
				       struct sk_buff *skb,
				       u32 *_abort_code)
{
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	const struct rxrpc_key_token *token;
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	struct rxkad_level2_hdr sechdr;
	struct rxrpc_skb_priv *sp;
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_crypt iv;
	struct scatterlist _sg[4], *sg;
	struct sk_buff *trailer;
	u32 data_size, buf;
	u16 check;
	int nsg;

	_enter(",{%d}", skb->len);

	sp = rxrpc_skb(skb);

	/* we want to decrypt the skbuff in-place */
	nsg = skb_cow_data(skb, 0, &trailer);
	if (nsg < 0)
		goto nomem;

	sg = _sg;
	if (unlikely(nsg > 4)) {
		sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO);
		if (!sg)
			goto nomem;
	}

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	sg_init_table(sg, nsg);
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	skb_to_sgvec(skb, sg, 0, skb->len);
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	/* decrypt from the session key */
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	token = call->conn->params.key->payload.data[0];
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	memcpy(&iv, token->kad->session_key, sizeof(iv));
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, skb->len, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);
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	if (sg != _sg)
		kfree(sg);

	/* remove the decrypted packet length */
	if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
		goto datalen_error;
	if (!skb_pull(skb, sizeof(sechdr)))
		BUG();

	buf = ntohl(sechdr.data_size);
	data_size = buf & 0xffff;

	check = buf >> 16;
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	check ^= sp->hdr.seq ^ sp->hdr.callNumber;
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	check &= 0xffff;
	if (check != 0) {
		*_abort_code = RXKADSEALEDINCON;
		goto protocol_error;
	}

	/* shorten the packet to remove the padding */
	if (data_size > skb->len)
		goto datalen_error;
	else if (data_size < skb->len)
		skb->len = data_size;

	_leave(" = 0 [dlen=%x]", data_size);
	return 0;

datalen_error:
	*_abort_code = RXKADDATALEN;
protocol_error:
	_leave(" = -EPROTO");
	return -EPROTO;

nomem:
	_leave(" = -ENOMEM");
	return -ENOMEM;
}

/*
 * verify the security on a received packet
 */
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static int rxkad_verify_packet(struct rxrpc_call *call,
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			       struct sk_buff *skb,
			       u32 *_abort_code)
{
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	SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher);
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	struct rxrpc_skb_priv *sp;
	struct rxrpc_crypt iv;
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	struct scatterlist sg;
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	u16 cksum;
	u32 x, y;
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	int ret;

	sp = rxrpc_skb(skb);

	_enter("{%d{%x}},{#%u}",
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	       call->debug_id, key_serial(call->conn->params.key), sp->hdr.seq);
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	if (!call->conn->cipher)
		return 0;

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	if (sp->hdr.securityIndex != RXRPC_SECURITY_RXKAD) {
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		*_abort_code = RXKADINCONSISTENCY;
		_leave(" = -EPROTO [not rxkad]");
		return -EPROTO;
	}

	/* continue encrypting from where we left off */
	memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));

	/* validate the security checksum */
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	x = call->channel << (32 - RXRPC_CIDSHIFT);
	x |= sp->hdr.seq & 0x3fffffff;
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	call->crypto_buf[0] = htonl(call->call_id);
	call->crypto_buf[1] = htonl(x);
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	sg_init_one(&sg, call->crypto_buf, 8);
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	skcipher_request_set_tfm(req, call->conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
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	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
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	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
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	y = ntohl(call->crypto_buf[1]);
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	cksum = (y >> 16) & 0xffff;
	if (cksum == 0)
		cksum = 1; /* zero checksums are not permitted */
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	if (sp->hdr.cksum != cksum) {
		*_abort_code = RXKADSEALEDINCON;
		_leave(" = -EPROTO [csum failed]");
		return -EPROTO;
	}

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	switch (call->conn->params.security_level) {
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	case RXRPC_SECURITY_PLAIN:
		ret = 0;
		break;
	case RXRPC_SECURITY_AUTH:
		ret = rxkad_verify_packet_auth(call, skb, _abort_code);
		break;
	case RXRPC_SECURITY_ENCRYPT:
		ret = rxkad_verify_packet_encrypt(call, skb, _abort_code);
		break;
	default:
		ret = -ENOANO;
		break;
	}

	_leave(" = %d", ret);
	return ret;
}

/*
 * issue a challenge
 */
static int rxkad_issue_challenge(struct rxrpc_connection *conn)
{
	struct rxkad_challenge challenge;
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	struct rxrpc_wire_header whdr;
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	struct msghdr msg;
	struct kvec iov[2];
	size_t len;
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	u32 serial;
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	int ret;

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	_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
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	ret = key_validate(conn->params.key);
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	if (ret < 0)
		return ret;

	get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));

	challenge.version	= htonl(2);
	challenge.nonce		= htonl(conn->security_nonce);
	challenge.min_level	= htonl(0);
	challenge.__padding	= 0;

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	msg.msg_name	= &conn->params.peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(conn->params.peer->srx.transport.sin);
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	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

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	whdr.epoch	= htonl(conn->proto.epoch);
	whdr.cid	= htonl(conn->proto.cid);
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	whdr.callNumber	= 0;
	whdr.seq	= 0;
	whdr.type	= RXRPC_PACKET_TYPE_CHALLENGE;
	whdr.flags	= conn->out_clientflag;
	whdr.userStatus	= 0;
	whdr.securityIndex = conn->security_ix;
	whdr._rsvd	= 0;
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	whdr.serviceId	= htons(conn->params.service_id);
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	iov[0].iov_base	= &whdr;
	iov[0].iov_len	= sizeof(whdr);
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	iov[1].iov_base	= &challenge;
	iov[1].iov_len	= sizeof(challenge);

	len = iov[0].iov_len + iov[1].iov_len;

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	serial = atomic_inc_return(&conn->serial);
	whdr.serial = htonl(serial);
	_proto("Tx CHALLENGE %%%u", serial);
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	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
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	if (ret < 0) {
		_debug("sendmsg failed: %d", ret);
		return -EAGAIN;
	}

	_leave(" = 0");
	return 0;
}

/*
 * send a Kerberos security response
 */
static int rxkad_send_response(struct rxrpc_connection *conn,
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			       struct rxrpc_host_header *hdr,
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			       struct rxkad_response *resp,
			       const struct rxkad_key *s2)
{
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	struct rxrpc_wire_header whdr;
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	struct msghdr msg;
	struct kvec iov[3];
	size_t len;
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	u32 serial;
629 630 631 632
	int ret;

	_enter("");

633 634
	msg.msg_name	= &conn->params.peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(conn->params.peer->srx.transport.sin);
635 636 637 638
	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

639 640 641 642 643 644 645
	memset(&whdr, 0, sizeof(whdr));
	whdr.epoch	= htonl(hdr->epoch);
	whdr.cid	= htonl(hdr->cid);
	whdr.type	= RXRPC_PACKET_TYPE_RESPONSE;
	whdr.flags	= conn->out_clientflag;
	whdr.securityIndex = hdr->securityIndex;
	whdr.serviceId	= htons(hdr->serviceId);
646

647 648
	iov[0].iov_base	= &whdr;
	iov[0].iov_len	= sizeof(whdr);
649 650
	iov[1].iov_base	= resp;
	iov[1].iov_len	= sizeof(*resp);
651
	iov[2].iov_base	= (void *)s2->ticket;
652 653 654 655
	iov[2].iov_len	= s2->ticket_len;

	len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;

656 657 658
	serial = atomic_inc_return(&conn->serial);
	whdr.serial = htonl(serial);
	_proto("Tx RESPONSE %%%u", serial);
659

660
	ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len);
661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691
	if (ret < 0) {
		_debug("sendmsg failed: %d", ret);
		return -EAGAIN;
	}

	_leave(" = 0");
	return 0;
}

/*
 * calculate the response checksum
 */
static void rxkad_calc_response_checksum(struct rxkad_response *response)
{
	u32 csum = 1000003;
	int loop;
	u8 *p = (u8 *) response;

	for (loop = sizeof(*response); loop > 0; loop--)
		csum = csum * 0x10204081 + *p++;

	response->encrypted.checksum = htonl(csum);
}

/*
 * encrypt the response packet
 */
static void rxkad_encrypt_response(struct rxrpc_connection *conn,
				   struct rxkad_response *resp,
				   const struct rxkad_key *s2)
{
H
Herbert Xu 已提交
692
	SKCIPHER_REQUEST_ON_STACK(req, conn->cipher);
693
	struct rxrpc_crypt iv;
694
	struct scatterlist sg[1];
695 696 697 698

	/* continue encrypting from where we left off */
	memcpy(&iv, s2->session_key, sizeof(iv));

699 700
	sg_init_table(sg, 1);
	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
H
Herbert Xu 已提交
701 702 703 704 705
	skcipher_request_set_tfm(req, conn->cipher);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
	crypto_skcipher_encrypt(req);
	skcipher_request_zero(req);
706 707 708 709 710 711 712 713 714
}

/*
 * respond to a challenge packet
 */
static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
				      struct sk_buff *skb,
				      u32 *_abort_code)
{
715
	const struct rxrpc_key_token *token;
716 717 718 719 720 721 722
	struct rxkad_challenge challenge;
	struct rxkad_response resp
		__attribute__((aligned(8))); /* must be aligned for crypto */
	struct rxrpc_skb_priv *sp;
	u32 version, nonce, min_level, abort_code;
	int ret;

723
	_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
724

725
	if (!conn->params.key) {
726 727 728 729
		_leave(" = -EPROTO [no key]");
		return -EPROTO;
	}

730
	ret = key_validate(conn->params.key);
731 732 733 734 735 736 737 738 739 740 741 742 743 744 745
	if (ret < 0) {
		*_abort_code = RXKADEXPIRED;
		return ret;
	}

	abort_code = RXKADPACKETSHORT;
	sp = rxrpc_skb(skb);
	if (skb_copy_bits(skb, 0, &challenge, sizeof(challenge)) < 0)
		goto protocol_error;

	version = ntohl(challenge.version);
	nonce = ntohl(challenge.nonce);
	min_level = ntohl(challenge.min_level);

	_proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
746
	       sp->hdr.serial, version, nonce, min_level);
747 748 749 750 751 752

	abort_code = RXKADINCONSISTENCY;
	if (version != RXKAD_VERSION)
		goto protocol_error;

	abort_code = RXKADLEVELFAIL;
753
	if (conn->params.security_level < min_level)
754 755
		goto protocol_error;

756
	token = conn->params.key->payload.data[0];
757 758 759 760

	/* build the response packet */
	memset(&resp, 0, sizeof(resp));

761
	resp.version			= htonl(RXKAD_VERSION);
762 763
	resp.encrypted.epoch		= htonl(conn->proto.epoch);
	resp.encrypted.cid		= htonl(conn->proto.cid);
764 765
	resp.encrypted.securityIndex	= htonl(conn->security_ix);
	resp.encrypted.inc_nonce	= htonl(nonce + 1);
766
	resp.encrypted.level		= htonl(conn->params.security_level);
767 768 769
	resp.kvno			= htonl(token->kad->kvno);
	resp.ticket_len			= htonl(token->kad->ticket_len);

770 771 772 773
	resp.encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
	resp.encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
	resp.encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
	resp.encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
774 775 776

	/* calculate the response checksum and then do the encryption */
	rxkad_calc_response_checksum(&resp);
777 778
	rxkad_encrypt_response(conn, &resp, token->kad);
	return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794

protocol_error:
	*_abort_code = abort_code;
	_leave(" = -EPROTO [%d]", abort_code);
	return -EPROTO;
}

/*
 * decrypt the kerberos IV ticket in the response
 */
static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
				void *ticket, size_t ticket_len,
				struct rxrpc_crypt *_session_key,
				time_t *_expiry,
				u32 *_abort_code)
{
H
Herbert Xu 已提交
795
	struct skcipher_request *req;
796
	struct rxrpc_crypt iv, key;
797
	struct scatterlist sg[1];
798
	struct in_addr addr;
799
	unsigned int life;
800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820
	time_t issue, now;
	bool little_endian;
	int ret;
	u8 *p, *q, *name, *end;

	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));

	*_expiry = 0;

	ret = key_validate(conn->server_key);
	if (ret < 0) {
		switch (ret) {
		case -EKEYEXPIRED:
			*_abort_code = RXKADEXPIRED;
			goto error;
		default:
			*_abort_code = RXKADNOAUTH;
			goto error;
		}
	}

821
	ASSERT(conn->server_key->payload.data[0] != NULL);
822 823
	ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);

824
	memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
825

H
Herbert Xu 已提交
826 827 828 829 830 831 832
	req = skcipher_request_alloc(conn->server_key->payload.data[0],
				     GFP_NOFS);
	if (!req) {
		*_abort_code = RXKADNOAUTH;
		ret = -ENOMEM;
		goto error;
	}
833

834
	sg_init_one(&sg[0], ticket, ticket_len);
H
Herbert Xu 已提交
835 836 837 838
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_free(req);
839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878

	p = ticket;
	end = p + ticket_len;

#define Z(size)						\
	({						\
		u8 *__str = p;				\
		q = memchr(p, 0, end - p);		\
		if (!q || q - p > (size))		\
			goto bad_ticket;		\
		for (; p < q; p++)			\
			if (!isprint(*p))		\
				goto bad_ticket;	\
		p++;					\
		__str;					\
	})

	/* extract the ticket flags */
	_debug("KIV FLAGS: %x", *p);
	little_endian = *p & 1;
	p++;

	/* extract the authentication name */
	name = Z(ANAME_SZ);
	_debug("KIV ANAME: %s", name);

	/* extract the principal's instance */
	name = Z(INST_SZ);
	_debug("KIV INST : %s", name);

	/* extract the principal's authentication domain */
	name = Z(REALM_SZ);
	_debug("KIV REALM: %s", name);

	if (end - p < 4 + 8 + 4 + 2)
		goto bad_ticket;

	/* get the IPv4 address of the entity that requested the ticket */
	memcpy(&addr, p, sizeof(addr));
	p += 4;
H
Harvey Harrison 已提交
879
	_debug("KIV ADDR : %pI4", &addr);
880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901

	/* get the session key from the ticket */
	memcpy(&key, p, sizeof(key));
	p += 8;
	_debug("KIV KEY  : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
	memcpy(_session_key, &key, sizeof(key));

	/* get the ticket's lifetime */
	life = *p++ * 5 * 60;
	_debug("KIV LIFE : %u", life);

	/* get the issue time of the ticket */
	if (little_endian) {
		__le32 stamp;
		memcpy(&stamp, p, 4);
		issue = le32_to_cpu(stamp);
	} else {
		__be32 stamp;
		memcpy(&stamp, p, 4);
		issue = be32_to_cpu(stamp);
	}
	p += 4;
902
	now = get_seconds();
903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
	_debug("KIV ISSUE: %lx [%lx]", issue, now);

	/* check the ticket is in date */
	if (issue > now) {
		*_abort_code = RXKADNOAUTH;
		ret = -EKEYREJECTED;
		goto error;
	}

	if (issue < now - life) {
		*_abort_code = RXKADEXPIRED;
		ret = -EKEYEXPIRED;
		goto error;
	}

	*_expiry = issue + life;

	/* get the service name */
	name = Z(SNAME_SZ);
	_debug("KIV SNAME: %s", name);

	/* get the service instance name */
	name = Z(INST_SZ);
	_debug("KIV SINST: %s", name);

	ret = 0;
error:
	_leave(" = %d", ret);
	return ret;

bad_ticket:
	*_abort_code = RXKADBADTICKET;
	ret = -EBADMSG;
	goto error;
}

/*
 * decrypt the response packet
 */
static void rxkad_decrypt_response(struct rxrpc_connection *conn,
				   struct rxkad_response *resp,
				   const struct rxrpc_crypt *session_key)
{
H
Herbert Xu 已提交
946
	SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci);
947
	struct scatterlist sg[1];
948 949 950 951 952 953 954 955
	struct rxrpc_crypt iv;

	_enter(",,%08x%08x",
	       ntohl(session_key->n[0]), ntohl(session_key->n[1]));

	ASSERT(rxkad_ci != NULL);

	mutex_lock(&rxkad_ci_mutex);
H
Herbert Xu 已提交
956 957
	if (crypto_skcipher_setkey(rxkad_ci, session_key->x,
				   sizeof(*session_key)) < 0)
958 959 960 961
		BUG();

	memcpy(&iv, session_key, sizeof(iv));

962 963
	sg_init_table(sg, 1);
	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
H
Herbert Xu 已提交
964 965 966 967 968 969
	skcipher_request_set_tfm(req, rxkad_ci);
	skcipher_request_set_callback(req, 0, NULL, NULL);
	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
	crypto_skcipher_decrypt(req);
	skcipher_request_zero(req);

970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987
	mutex_unlock(&rxkad_ci_mutex);

	_leave("");
}

/*
 * verify a response
 */
static int rxkad_verify_response(struct rxrpc_connection *conn,
				 struct sk_buff *skb,
				 u32 *_abort_code)
{
	struct rxkad_response response
		__attribute__((aligned(8))); /* must be aligned for crypto */
	struct rxrpc_skb_priv *sp;
	struct rxrpc_crypt session_key;
	time_t expiry;
	void *ticket;
A
Al Viro 已提交
988 989
	u32 abort_code, version, kvno, ticket_len, level;
	__be32 csum;
990
	int ret, i;
991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004

	_enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));

	abort_code = RXKADPACKETSHORT;
	if (skb_copy_bits(skb, 0, &response, sizeof(response)) < 0)
		goto protocol_error;
	if (!pskb_pull(skb, sizeof(response)))
		BUG();

	version = ntohl(response.version);
	ticket_len = ntohl(response.ticket_len);
	kvno = ntohl(response.kvno);
	sp = rxrpc_skb(skb);
	_proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
1005
	       sp->hdr.serial, version, kvno, ticket_len);
1006 1007 1008

	abort_code = RXKADINCONSISTENCY;
	if (version != RXKAD_VERSION)
D
David Howells 已提交
1009
		goto protocol_error;
1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040

	abort_code = RXKADTICKETLEN;
	if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
		goto protocol_error;

	abort_code = RXKADUNKNOWNKEY;
	if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
		goto protocol_error;

	/* extract the kerberos ticket and decrypt and decode it */
	ticket = kmalloc(ticket_len, GFP_NOFS);
	if (!ticket)
		return -ENOMEM;

	abort_code = RXKADPACKETSHORT;
	if (skb_copy_bits(skb, 0, ticket, ticket_len) < 0)
		goto protocol_error_free;

	ret = rxkad_decrypt_ticket(conn, ticket, ticket_len, &session_key,
				   &expiry, &abort_code);
	if (ret < 0) {
		*_abort_code = abort_code;
		kfree(ticket);
		return ret;
	}

	/* use the session key from inside the ticket to decrypt the
	 * response */
	rxkad_decrypt_response(conn, &response, &session_key);

	abort_code = RXKADSEALEDINCON;
1041
	if (ntohl(response.encrypted.epoch) != conn->proto.epoch)
1042
		goto protocol_error_free;
1043
	if (ntohl(response.encrypted.cid) != conn->proto.cid)
1044 1045 1046 1047 1048 1049 1050 1051 1052
		goto protocol_error_free;
	if (ntohl(response.encrypted.securityIndex) != conn->security_ix)
		goto protocol_error_free;
	csum = response.encrypted.checksum;
	response.encrypted.checksum = 0;
	rxkad_calc_response_checksum(&response);
	if (response.encrypted.checksum != csum)
		goto protocol_error_free;

1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
	spin_lock(&conn->channel_lock);
	for (i = 0; i < RXRPC_MAXCALLS; i++) {
		struct rxrpc_call *call;
		u32 call_id = ntohl(response.encrypted.call_id[i]);

		if (call_id > INT_MAX)
			goto protocol_error_unlock;

		if (call_id < conn->channels[i].call_counter)
			goto protocol_error_unlock;
		if (call_id > conn->channels[i].call_counter) {
			call = rcu_dereference_protected(
				conn->channels[i].call,
				lockdep_is_held(&conn->channel_lock));
			if (call && call->state < RXRPC_CALL_COMPLETE)
				goto protocol_error_unlock;
			conn->channels[i].call_counter = call_id;
		}
	}
	spin_unlock(&conn->channel_lock);
1073 1074

	abort_code = RXKADOUTOFSEQUENCE;
1075
	if (ntohl(response.encrypted.inc_nonce) != conn->security_nonce + 1)
1076 1077 1078 1079 1080 1081
		goto protocol_error_free;

	abort_code = RXKADLEVELFAIL;
	level = ntohl(response.encrypted.level);
	if (level > RXRPC_SECURITY_ENCRYPT)
		goto protocol_error_free;
1082
	conn->params.security_level = level;
1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096

	/* create a key to hold the security data and expiration time - after
	 * this the connection security can be handled in exactly the same way
	 * as for a client connection */
	ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
	if (ret < 0) {
		kfree(ticket);
		return ret;
	}

	kfree(ticket);
	_leave(" = 0");
	return 0;

1097 1098
protocol_error_unlock:
	spin_unlock(&conn->channel_lock);
1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
protocol_error_free:
	kfree(ticket);
protocol_error:
	*_abort_code = abort_code;
	_leave(" = -EPROTO [%d]", abort_code);
	return -EPROTO;
}

/*
 * clear the connection security
 */
static void rxkad_clear(struct rxrpc_connection *conn)
{
	_enter("");

	if (conn->cipher)
H
Herbert Xu 已提交
1115
		crypto_free_skcipher(conn->cipher);
1116 1117
}

1118 1119 1120 1121 1122 1123 1124 1125
/*
 * Initialise the rxkad security service.
 */
static int rxkad_init(void)
{
	/* pin the cipher we need so that the crypto layer doesn't invoke
	 * keventd to go get it */
	rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
W
Wu Fengguang 已提交
1126
	return PTR_ERR_OR_ZERO(rxkad_ci);
1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137
}

/*
 * Clean up the rxkad security service.
 */
static void rxkad_exit(void)
{
	if (rxkad_ci)
		crypto_free_skcipher(rxkad_ci);
}

1138 1139 1140
/*
 * RxRPC Kerberos-based security
 */
1141
const struct rxrpc_security rxkad = {
1142
	.name				= "rxkad",
1143
	.security_index			= RXRPC_SECURITY_RXKAD,
1144 1145
	.init				= rxkad_init,
	.exit				= rxkad_exit,
1146 1147 1148 1149 1150 1151 1152 1153 1154
	.init_connection_security	= rxkad_init_connection_security,
	.prime_packet_security		= rxkad_prime_packet_security,
	.secure_packet			= rxkad_secure_packet,
	.verify_packet			= rxkad_verify_packet,
	.issue_challenge		= rxkad_issue_challenge,
	.respond_to_challenge		= rxkad_respond_to_challenge,
	.verify_response		= rxkad_verify_response,
	.clear				= rxkad_clear,
};